The M22 is designed to work with traditional phones, as well as wideband VoIP phones and phone systems. Newly incorporated “Clearline Technology” offers superior call clarity while providing advanced echo management, consistent and comfortable call volume, reduced background noise and protection against loud sounds.
Specs on Wideband:
Wideband Technology refers to the audible frequency range for telephony.
Traditional telephone systems operate between 300Hz and 3400Hz – Narrowband
New telephone systems and VoIP can operate between 150Hz and 6800Hz – Wideband
Special Notes on M22
Sleep Mode: When powered by batteries, the M22 enters “Sleep Mode” between calls to prolong battery life. The amplifier/headset will be inactive when you try to take a call. Press either the headset or mute button twice to “wake the amplifier.” The M22 will not enter sleep mode when powered by a DC adapter (part number 26503-01, shown in Figure 1).
Clicking (If you are experiencing a clicking sound like a steady heartbeat while on the headset):
1) Make sure the compatibility setting is securely on 5 (or whichever setting works with your phone). Next, move the
switch to another number, then switch right back to the original setting and see if the noise goes away.
2) Try new batteries.
3) Check to see if there is a cell phone or wireless router near by. If so, test the M22 on another phone away from
these devices to see if the pulsating continues.
Basic Troubleshooting (see Figure 2 at right):
1) Try new batteries: Battery life ranges from 6-9 months on average.
2) Check the compatibility settings: Most phones work best on 5 or 1. Sometimes other settings will work as
well. Setting 4 was designed as a battery test switch. In most cases, if you can hear them at all on this setting,
the batteries will need to be replaced.
3) Check the volume controls: The dial on top of the M22 controls listening volume. Adjusting the phone volume
will also change the listening level. The blue & white microphone “screw” on the left side of the amp (next to
compatibility switch) controls microphone volume.
4) Check the voicetube (All Voicetubes Discontinued!): If the headset has a voicetube, simply slide it off and speak directly into the microphone. If
the sound quality improves, the voicetube is either clogged or needs to be replaced. You may be able to un-
clog the tube with compressed air.